After the death of the Buddha, Buddhists thought, to the extent they understood the Buddha’s personality to be in conformity with his actual existence, that his body had to express perfection. The Dīgha-Nikāya lists ten epithets of the Buddha:

“Thus the World-Honored One is called Arhat, Fully Enlightened One, One Endowed with Knowledge and Action, Sugata, Lokavid, Supreme among Beings, Tamer of People, Teacher of People and Deities, Buddha, World-Honored One. He has realized and teaches concerning this world, including the heavens, the Māra realms, and the Brahma heavens, samaṇas, brahmans, heavenly beings, and human beings. He preaches the Dhamma which is good at the beginning, good in the middle, and good at the end, endowed with words and meaning, explaining the pure brahma conduct that is perfect, without fault. How good it is to see such a man of truth!”
(Dīgha-Nikāya, i, 87-88)

These are the basis of the expanded form of the Tathāgata’s ten epithets known in later times:

1. Tathāgata (not included in the Dīgha-Nikāya): one who has come from Thusness, one who has attained the Truth.
2. Arhat: one who has quelled all the defilements, one who is worthy of receiving the offerings of humankind and deities.
3. Samyak-saṃbuddha: one who is fully enlightened, one who has penetrated all truths and knows all that there is to be known.
4. Vidyā-caraṇa-sampanna: one who is endowed with wisdom (the three transcendental knowledges) and practice (physical, oral, mental).
5. Sugata: one who has truly crossed to the other shore of liberation, who will never again sink into the sea of saṃsāra of the defilements.
6. Lokavid: one who knows all about worldly existence.
7. Anuttara: the supreme among human beings.
8. Puruṣa-damya-sārathi: “the tamer of people,” one who teaches beings and causes them to enter the way of practice.
9. Śāstā devamanuṣyāṇām: a teacher of people and deities by means of the Right Dharma.
10. Buddha-bhagavat: “Buddha” is one who knows and sees the ultimate truth of all characteristics, and who has attained supreme and perfect enlightenment. “Bhagavat” is one who, possessing all merits, benefits beings everywhere, and is honored by the world.